Pressure container and process for producing and filling a pressure container

ABSTRACT

The present invention relates to a pressure container and to a process for producing and filling a pressure container. In this context, the pressure container has an outer container ( 20 ) and an inner container ( 10 ) located in the outer container ( 20 ). The inner container ( 10 ) includes a wall ( 13 ) consisting of a laminated film. There is a content chamber ( 11 ) for contents ( 12 ) in the inner container ( 10 ) and there is a propellant chamber ( 21 ) for a propellant ( 22 ) in the outer container ( 20 ). Both containers are separated from each other such that they are fluid-tight and/or gas-tight. A cover part ( 25 ) seals the containers ( 10, 20 ). There is a valve part ( 30 ) on the cover part ( 25 ) for dispensing contents ( 12 ) from the content chamber ( 11 ) to the outside. There is a closable filling opening ( 27 ) in a bottom part ( 26 ) of the outer container ( 20 ) that faces away from the valve part ( 30 ). To improve such a pressure container, the inner container ( 10 ) has a bottom weld ( 14 ) at which location the inner container ( 10 ) is welded and/or glued, and the inner container ( 10 ) is folded in a lower section ( 15 ) facing its bottom weld ( 14 ) to form a crescent-shaped cross sectional contour ( 16 ), before the inner container is inserted into the outer container ( 20 ) and before the propellant ( 22 ) is introduced into the outer container ( 20 ).

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a pressure container having an outer container including a propellant chamber for a propellant, an inner container located in the outer container and a cover part for sealing the containers with a valve part arranged thereon for dispensing contents from a content chamber in the inner container to the outside. The inner container has a bottom weld at which location the inner container is welded and/or glued, and the inner container, before being inserted into the outer container and before the propellant is introduced into the outer container, receives a crescent-shaped cross sectional contour at least in a lower section facing the bottom weld. The invention also relates to a process for producing and filling such a pressure container comprising the steps of providing the inner container with a bottom weld at which location the inner container is welded and/or glued; folding the inner container in a lower section facing the bottom weld to form a crescent-shaped cross sectional contour; inserting the inner container into the outer container; and introducing propellant into the outer container.

[0002] Liquid hydrocarbons stored in pressure containers are used to power fastening devices. The replaceable pressure containers or gas cans are fitted with a metering head that is attached to the gas can by a snap-on connection. The system of the pressure container and the gas can with the metering head is then inserted into the fastening device. The system constantly provides the fuel gas in the liquid phase for metering by the metering head. Similar demands are also made of the pressure container for other applications, since the dispensing of gas in the liquid phase is always desirable in devices involving liquefied gas metering. However, it is also desirable to achieve the highest possible filling volume for the contents or fuel in the pressure container.

[0003] German patent application DE 195 16 100 A1 discloses a process for producing or filling a pressure container wherein the inner container rolls upwards towards the valve while it is in the unfilled state, i.e. before the propellant has been filled into the outer container. In this manner, a relatively large inner container can be used to hold a greater volume of contents. When the outer container is filled with propellant, the inner container that has been rolled up cannot be damaged by the filling needle that is inserted through the filling opening in the bottom area of the outer container.

[0004] A disadvantage of this process, however, is that such a process cannot be used with inner containers made of laminated films. As a rule, such laminated films consist of an inner and an outer plastic layer with a metal foil or metal layer between such layers. Such inner containers are necessary for storing fuel gases since bags made of pure plastic allow a diffusion of the gas molecules. With these laminated films, however, the metal foil or metal layer is damaged when it is rolled up, and as a result the tightness against diffusion is no longer ensured.

SUMMARY OF THE INVENTION

[0005] It is the object of the present invention to develop a pressure container and a process for producing and filling a pressure container in which the pressure container entails the largest possible volume for the inner container and the pressure container avoids the above-mentioned drawbacks. This is achieved according to the invention by a pressure container a process for producing and filling such a pressure container having an outer container including a propellant chamber for a propellant, an inner container located in the outer container and a cover part for sealing the containers with a valve part arranged thereon for dispensing contents from a content chamber in the inner container to the outside. The inner container has a bottom weld at which location the inner container is welded and/or glued, and the inner container, before being inserted into the outer container and before the propellant is introduced into the outer container, receives a crescent-shaped cross sectional contour at least in a lower section facing the bottom weld.

[0006] An important feature of the present invention is that the lower area of the wall of the inner container is collapsed or folded so as to acquire a crescent-shaped or U-shaped outer contour before the inner container is inserted into the outer container. The enveloping circle of the inner container thus folded is somewhat smaller than the inner diameter of the outer container into which the inner container has to be inserted and attached. The length of the inner container, however, essentially matches the inner length of the outer container so that the upper edges of the outer and inner containers lie almost flush with each other after the inner container has been inserted into the outer container. Once all of the parts of the pressure container have been assembled, the outer container can be filled through the filling opening located in the bottom part of the outer container using a hollow needle. As a result of the step of collapsing the inner container to be crescent-shaped or U-shaped, despite the size of the inner container, there is no risk that the inner container will be damaged by the hollow needle since the lower area of the inner container encircles the axial projection of the filling opening and thus of the hollow needle.

[0007] Preferably, the bottom weld of the inner container is eccentrically arranged at the lower end of the inner container. Such an arrangement facilitates the collapsing of the inner container.

[0008] Preferably, the inner container has the appropriate length to stand on the bottom of the outer container during the assembly of the can such that the entire length of the container can be utilized for the contents and the inner container does not have to be positioned during the crimping procedure. As a result, cost savings are possible.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Additional advantages and measures of the invention are described below with reference to the drawings wherein:

[0010]FIG. 1 shows a longitudinal sectional view of a pressure container, in accordance with the invention, in the unfilled state;

[0011]FIG. 2 shows a cross section of the pressure container of FIG. 1, in accordance with the invention, along the plane 11-11 of FIG. 1, in the unfilled state;

[0012]FIG. 3 shows a longitudinal sectional view of the pressure container of FIG. 1, in accordance with the invention, in the filled state, and

[0013]FIG. 4 shows a sectional enlargement of area IV of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

[0014] FIGS. 1 to 3 show a pressure container according to the invention that comprises an outer container 20 and an inner container 10. In this embodiment, the outer container 20 is made of a relatively thick-walled metal material such as aluminum, whereas the inner container 10 has a wall 13 made of a relatively thin-walled laminated film. This laminated film consists, for example, of the three layers, as shown in FIG. 4: an inner plastic layer 19 such as a PE laminate layer, a metal layer or metal foil 18 and an outer plastic layer 17 such as a PE laminate layer. The metal layer that is made of aluminum serves as a barrier layer for liquid and gaseous media, i.e. the fuel gas. In the area of the opening 24, the two containers 10, 20 are attached to each other by means of a rolled collar 23 and sealed with respect to each other. The opening 24 is sealed against the outside by means of a cover part 25 so as to be media-tight. The inner container 10 comprises a content chamber 11 which holds dispensable contents 12 such as, for example, a flammable liquefied gas. The contents 12 such as, for example, a liquefied gas, are under the pressure of a propellant 22 that is held in the propellant chamber 21 of the outer container 20. The propellant is present in the propellant chamber 21 in a liquid phase and in a gaseous phase. In a passage in the cover part 25, there is a valve part 30 that is sealed with respect to the cover part 25. The valve part 30 has an inlet/outlet part via which the contents 12 or liquefied gas can be dispensed to the outside or into another device or metering element, metering means, etc. attached to the outlet part.

[0015] The inner container 10 is sealed with a bottom weld 14 at its lower end. In the present embodiment, this bottom weld 14 is arranged eccentrically on the inner container 10. In a lower section 15, the inner container in the unfilled state, as shown in FIGS. 1 and 2, receives a crescent-shaped cross sectional contour 16. The inner container 10 lies in the bottom part 26 of the outer container 20, in the area of the lower section 15, due to the crescent-shaped cross section 16 outside of the axial projection 28 of an inlet opening 27. The lower section 15 of the inner container 10 has a concave wall section 46 facing the axial projection 28 and a convex wall section 47 facing away from the axial projection 28.

[0016] The inlet opening 27 is provided with a sealing plug 29 preferably made of rubber. In order to fill the outer container 20 with propellant 22, a hollow needle 40, for example, can be inserted through the sealing plug 29 through which the propellant 22 can then be filled from a reservoir into the propellant chamber 21.

[0017] A pressure pack according to the invention can be produced as follows, for example: A laminated film is cut into a section of a certain length that matches the outer container 20 and welded with an overlap to form a conical or cylindrical tube. In a second step, the tube end is sealed by a mash weld to form the later inner container 10. This mash weld constitutes the bottom weld of the inner container 10. The open end of the inner container 10 has essentially the same diameter as the cover part 25 on which the valve part 30 has been arranged. In a third step, the inner container 10 is folded in the area of the bottom weld 14 to be essentially crescent-shaped or U-shaped.

[0018] Then in a fourth step, the inner container 10 is laid between the cover part 25 and the rolled collar 23 of the outer container 20 such that it stands on the bottom part 26 of the outer container 20 and lies flush with the opening 24 of the outer container 20. The inner container 10 is then crimped with the outer container 20 and with the cover part 25 and optionally with other sealing elements onto the rolled collar 23.

[0019] The pressure container shown in FIGS. 1 and 2 is thus formed. In a fifth step, propellant 22 is filled into the propellant chamber 21 of the outer container 20 via a hollow needle 40 that is indicated in FIG. 1. The contents 12 can then be filled into the inner container 10 via the valve part 30. The inner container 10 unfolds in this process and assumes the position and geometry depicted in FIG. 3. 

What is claimed is:
 1. A pressure container having an outer container (20); an inner container (10) with a wall (13) consisting of a laminated film located in the outer container (20) and a cover part (25) for sealing the containers (10, 20); wherein the inner container (10) includes a content chamber (11) for contents (12) and the outer container (20) includes a propellant chamber (21) for a propellant (22), the inner container (10) and the outer container (20) being separated from each other so as to be at least one of fluid-tight and gas-tight; wherein the cover part (25) has a valve part (30) arranged thereon for dispensing contents (12) from the content chamber (11) to the outside, and a closable filling opening (27) in a bottom part (26) of the outer container (20) faces away from the valve part (30); wherein the inner container (10) has a bottom weld (14) at which the inner container (10) is at least one of welded and glued, and the inner container (10), before being inserted into the outer container (20) and before the propellant (22) is introduced into the outer container (20), receives a crescent-shaped cross sectional contour (16) at least in a lower section (15) facing the bottom weld (14).
 2. The pressure container of claim 1, wherein the bottom weld (14) is arranged at a lower end of the inner container (10).
 3. A process for producing and filling a pressure container having an outer container (20) including a propellant chamber (21) for a propellant (22); an inner container (10) including a wall (13) consisting of a laminated film located and a content chamber (11) for contents (12), both containers being separated from each other to be at least one of fluid-tight and gas-tight; and a cover part (25) for sealing the containers (10, 20) having a valve part (30) arranged thereon for dispensing contents (12) from the content chamber (11) to the outside, a bottom part (26) of the outer container (20) having a closable filling opening (27) facing away from the valve part (30); comprising the steps of: providing the inner container (10) with a bottom weld (14) at which location the inner container (10) is one of welded and glued; folding the inner container (10) in a lower section (15) facing the bottom weld (14) to form a crescent-shaped cross sectional contour (16); inserting the inner container (10) into the outer container (20); introducing propellant (22) into the outer container (20).
 4. The process of claim 2, wherein the step of inserting the inner container (10) into the outer container (20) comprises the step of inserting the inner container (10) into the outer container (20) until the bottom weld (14) lies directly over the bottom part (26) such that the lower section (15) facing the bottom weld (14) lies outside of an axial projection (28) of the filling opening (27). 